<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 transitional//EN">
<html>
<head>
<title>Join Condition Structure</title>
<link rel="stylesheet" href="../style/style.css" type="text/css"/>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body>
<h1>JoinCondition</h1>

<p>Defines a join condition.</p>

<h3>Description</h3>

<p>User can define a joint data set which is a data set joined by several data sets on some join conditions,
The join condition is whether two expressions,left expression and right expression, satisfy a relationship 
defined by the join operator which can be equality, less than or greater than. Left expression is 
an expression of fields from left dataset, right expression is an expression of fields 
from right dataset.</p>

<p>For example, a condition can be:</p>
<p><pre>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dataSet1 inner join dataSet2 on 2 * column1 = 3 * column2</pre></p>
<p>"column1" is from the data set named "dataSet1", "coloumn2" is from "dataSet2".</p>
<p>This condition is defined by JoinCondition with following members:</p>
<table>
<tr><td width="20%"/><td>joinType</td><td>=</td><td>inner join</td></tr>
<tr><td width="20%"/><td>joinOperator</td><td>=</td><td>eq</td></tr>
<tr><td width="20%"/><td>leftDataSet</td><td>=</td><td>"dataSet1"</td></tr>
<tr><td width="20%"/><td>rightDataSet</td><td>=</td><td>"dataSet2"</td></tr>
<tr><td width="20%"/><td>leftExpression</td><td>=</td><td>"2 * column1"</td></tr>
<tr><td width="20%"/><td>rightExpression</td><td>=</td><td>"3 * column2"</td></tr>
</table>
</pre>
<h3>See Also</h3>

<h2 class="property">joinType</h2>

<p>The join type.</p>

<h3>Description</h3>

<p>The join type: inner join, left out join or right out join.</p>

<h3>See Also</h3>

<h2 class="property">joinOperator</h2>

<p>The comparator of the condition.</p>

<h3>Description</h3>

<p>The comparator of the condition: equals, less than or greater than.</p>

<h3>See Also</h3>

<h2 class="property">leftDataSet</h2>

<p>The name of left data set of the condition.</p>

<h3>Description</h3>

<p>The name of left data set of the condition.</p>

<h3>See Also</h3>
<h2 class="property">rightDataSet</h2>

<p>The name of right data set of the condition.</p>

<h3>Description</h3>

<p>The name of right data set of the condition.</p>

<h3>See Also</h3>
<h2 class="property">leftExpression</h2>

<p>The left expression of the condition.</p>

<h3>Description</h3>

<p>The left expression of the condition.</p>

<h3>See Also</h3>
<h2 class="property">rightExpression</h2>

<p>The right expression of the condition.</p>

<h3>Description</h3>

<p>The right expression of the condition.</p>

<h3>See Also</h3>
</body>
</html>